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Uranium(IV) solubility and hydrolysis constants under reduced conditions

Conference ·
OSTI ID:382893
; ;  [1]
  1. Mitsubishi Materials Corp., Naka, Ibaraki (Japan). Naka Energy Research Center
The solubility of UO{sub 2}(S) was examined in dilute NaCl solutions at room temperature and in the ph range from 2 to 12. Dissolution equilibrium showed good agreements between the data obtained by oversaturation and undersaturation experiments. The dissolution reactions that control the solubility of U[IV] are estimated as UO{sub 2} (s) + 4H{sup +} + 2H{sub 2}O and UO{sub 2} (s) + 2H{sub 2}O {yields} U(OH){sub 4}{sup 0}. The log K at zero ionic strength are yielded 0.34 {+-} 0.4 and {minus}8.7 {+-} 0.4, respectively. The hydrolysis constant (log {beta}{sub 14}) is calculated {minus}9.0 {+-} 0.5 for the hydrolysis reaction of U{sup 4+} + 4H{sub 2}O {yields} U(OH){sub 4}{sup 0} + 4H{sup +}. Contribution of the other uranium species to the solubility are of minor importance. The crystallization of the precipitations of UO{sub 2}(s) progressed gradually in the oversaturation experiments. Nevertheless the progress of crystallization had little effect on the solubility.
OSTI ID:
382893
Report Number(s):
CONF-941075--; ISBN 1-55899-253-7
Country of Publication:
United States
Language:
English